1. Field of the Invention
The present invention relates to a display device such as a liquid crystal display device and a method of manufacturing the same.
2. Description of the Related Art
In recent years, liquid crystal display devices are used as display devices for various electronic apparatuses such as a personal computer, a cellular phone, and a digital camera by virtue of advantages that the liquid crystal display devices are thin and consume less power. Such liquid crystal display devices are not self light-emitting display devices such as a CRT (Cathode Ray Tube) and an organic electroluminescence (organic EL) device and are roughly divided into a transmissive type and a reflective type.
A transmissive liquid crystal display device performs display using light of a lighting device (a back light) arranged behind a liquid crystal panel. A reflective liquid crystal display device performs display using ambient light. Since the transmissive liquid crystal display device performs display using light of the backlight, the transmissive liquid crystal display device has an advantage that, even if ambient light is weak, display at high luminance and contrast is possible without being affected by the light. However, since the backlight consumes almost a half of total power consumed by the transmissive liquid crystal display device, it is difficult to reduce power consumption. Moreover, when ambient light is strong, display looks dark and viewability is deteriorated.
On the other hand, since the reflective liquid crystal display device does not have a backlight, the reflective liquid crystal display device has an advantage that power consumption is extremely small. Thus, the reflective liquid crystal display device is effective as a display device carried to the outdoor. However, the reflective liquid crystal display device has a disadvantage that viewability is deteriorated in a dark environment of use.
In order to solve the problems of the transmissive liquid crystal display device and the reflective liquid crystal display device, a semi-transmissive (transflective) liquid crystal display device that uses both transmissive-type display and reflective-type display is proposed (see, for example, JP-A-2001-318377).
The semi-transmissive liquid crystal display device performs display using ambient light when the environment is bright and performs display using a backlight when the environment is dark. For improvement of the characteristics, when the semi-transmissive liquid crystal display device has both a reflective region and a transmissive region, the thickness of a liquid crystal layer of the transmissive region is designed to be about twice as large as the thickness of a liquid crystal layer of the reflective region.
As a kind of such a structure, a gap adjusting layer for adjusting the thickness of the liquid crystal layer of the reflective region is provided on a side where a color filter is formed. When the gap adjusting layer is provided, bonding of the color filer and a thin film transistor (hereinafter referred to as TFT) has to be taken into account to realize satisfactory characteristics. Thus, the reflective region is narrowed (see, for example, JP-A-2005-115315) and reflection characteristics are deteriorated.
When a mechanism for adjusting a gap is formed on the TFT side (see, for example, JP-A-2001-350158), the bonding with the color filter is improved. However, since the gap is adjusted by removing an insulating layer of the transmissive region, deterioration in a transmission quality due to roughness formed by signal lines or the like is caused. Moreover, since a contact hole is opened in an insulating layer below a reflection electrode, deterioration in the reflection characteristics is caused.